MacKinnon is a highly cited legal scholar.[3][4] She has been a visiting professor at various universities and regularly appears in public speaking events. On February 10, 2005, she attended the premiere of Inside Deep Throat (in which she is an interviewee) and took part in a panel discussion after the film.[5][6][7][8] On April 29, 2009, MacKinnon argued on the radio show Intelligence Squared U.S. for the proposition "it's wrong to pay for sex".[9]

MacKinnon's ideas may be divided into three central — although overlapping and ongoing — areas of focus: (1) sexual harassment, (2) pornography, and (3) international work. She has also devoted attention to social and political theory and methodology.[10]

According to an article published by Deborah Dinner in the March/April 2006 issue of Legal Affairs, MacKinnon first became interested in issues concerning sexual harassment when she heard that an administrative assistant at Cornell University resigned after being refused a transfer when she complained of her supervisor's harassing behavior, and then was denied unemployment benefits because she quit for "personal" reasons. It was at a consciousness-raising session about this and other women's workplace experiences, organized by Lin Farley as part of a Cornell class on women and work,[11] that the term "sexual harassment" was coined.[12]

In 1977, MacKinnon graduated from Yale Law School after having written a paper on sexual harassment for Professor Thomas I. Emerson. Two years later, MacKinnon published "Sexual Harassment of Working Women", arguing that sexual harassment is a form of sex discrimination under Title VII of the Civil Rights Act of 1964 and any other sex discrimination prohibition. While working on "Sexual Harassment", she shared draft copies with attorneys litigating early sexual harassment cases, including Nadine Taub, who represented Yale undergraduates in Alexander v. Yale, the first test case of MacKinnon's legal theory.[13][14]

In her book, MacKinnon argued that sexual harassment is sex discrimination because the act reinforces the social inequality of women to men (see, for example, pp. 116–18, 174). She distinguishes between two types of sexual harassment (see pp. 32–42): 1) "quid pro quo", meaning sexual harassment "in which sexual compliance is exchanged, or proposed to be exchanged, for an employment opportunity (p. 32)" and 2) the type of harassment that "arises when sexual harassment is a persistent condition of work (p. 32)". In 1980, the Equal Employment Opportunity Commission followed MacKinnon's framework in adopting guidelines prohibiting sexual harassment by prohibiting both quid pro quo harassment and hostile work environment harassment (see 29 C.F.R. § 1604.11(a)).

In 1986, the Supreme Court held in Meritor Savings Bank v. Vinson that sexual harassment may violate laws against sex discrimination. In Meritor, the Court recognized the distinction between quid pro quo sexual harassment and hostile workplace harassment. In a 2002 article, MacKinnon wrote:

"'Without question,' then-Justice Rehnquist wrote for a unanimous Court, 'when a supervisor sexually harasses a subordinate because of the subordinate's sex, that supervisor "discriminate[s]" on the basis of sex.' The D.C. Circuit, and women, had won. A new common law rule was established."[15]

MacKinnon's book, Sexual Harassment of Working Women: A Case of Sex Discrimination, is the eighth most-cited American legal book published since 1978, according to a study published by Fred Shapiro[who?] in January 2000.[citation needed]

MacKinnon, along with late feminist activist Andrea Dworkin, has been active in attempting to change legal postures towards pornography by framing it as a form of sex discrimination and, more recently, a form of human trafficking. She (and Dworkin) define pornography as follows:

"We define pornography as the graphic sexually explicit subordination of women through pictures and words that also includes (i) women are presented dehumanized as sexual objects, things, or commodities; or (ii) women are presented as sexual objects who enjoy humiliation or pain; or (iii) women are presented as sexual objects experiencing sexual pleasure in rape, incest or other sexual assault; or (iv) women are presented as sexual objects tied up, cut up or mutilated or bruised or physically hurt; or (v) women are presented in postures or positions of sexual submission, servility, or display; or (vi) women's body parts—including but not limited to vaginas, breasts, or buttocks — are exhibited such that women are reduced to those parts; or (vii) women are presented being penetrated by objects or animals; or (viii) women are presented in scenarios of degradation, humiliation, injury, torture, shown as filthy or inferior, bleeding, bruised, or hurt in a context that makes these conditions sexual."

MacKinnon characterizes pornography as a particularly graphic and violent means of subordinating women. In Toward a Feminist Theory of the State, she writes, “Pornography, in the feminist view, is a form of forced sex, a practice of sexual politics, and institution of gender inequality.” MacKinnon chooses a few points to focus on specifically, depicting the sexual exploitation of women as a means of showing their inferiority by displaying them as sexual objects, things or commodities, which dehumanizes them. She argues that any display of women enjoying humiliation or pain should be a violation of the law. She writes, “Pornography contributes causally to attitudes and behaviors of violence and discrimination which define the treatment and status of half the population.”[citation needed]

Mackinnon holds that up until now, obscenity laws are the ways that the liberal state has attempted to regulate pornography. She states that the liberal state views obscenity as a form of expression under the First Amendment but MacKinnon disagrees with this view. Obscenity is concerned with morality, “good and evil, virtues and vices.” She posits that feminism approaches pornography from a political standpoint, while the obscenity law focuses on morality. “The concerns of feminism with power and powerlessness are first political, not moral.” MacKinnon states that obscenity is about morality, and pornography is “a political practice.”[citation needed]

In 1980, Linda Boreman (who had appeared, under the name Linda Lovelace in the pornographic film Deep Throat) claimed her ex-husband Chuck Traynor had violently coerced her into making Deep Throat and other pornographic films. Boreman made her charges public for the press corps at a press conference, together with MacKinnon, members of Women Against Pornography, and feminist writer Andrea Dworkin offering statements in support. After the press conference, Dworkin, MacKinnon, Boreman, and Gloria Steinem began discussing the possibility of using federal civil rights law to seek damages from Traynor and the makers of Deep Throat. Boreman was interested but backed off after Steinem discovered that the statute of limitations for a possible suit had passed (Brownmiller 337).

MacKinnon and Dworkin continued to discuss civil rights litigation as a possible approach to combating pornography. MacKinnon opposed traditional arguments against pornography based on the idea of morality or sexual innocence, as well as the use of traditional criminal obscenity law to suppress pornography. Instead of condemning pornography for violating "community standards" of sexual decency or modesty, they characterized pornography as a form of sex discrimination and sought to give women the right to seek damages under civil rights law. “Pornography, in the feminist view is a form of forced sex, a practice of sexual politics, an institution of gender inequality” (Mackinnon 197).[16]

In 1983, the Minneapolis city government hired MacKinnon and Dworkin to draft an antipornography civil rights ordinance as an amendment to the Minneapolis city civil rights ordinance. The amendment defined pornography as a civil rights violation against women and allowed women who claimed harm from pornography to sue the producers and distributors for damages in civil court. The law was passed twice by the Minneapolis city council but vetoed by the mayor. Another version of the ordinance passed in Indianapolis, Indiana in 1984, but was ruled unconstitutional by the Seventh Circuit Court of Appeals. MacKinnon continued to support the civil rights approach in her writing and activism, and supported anti-pornography feminists who organized later campaigns in Cambridge, Massachusetts (1985) and Bellingham, Washington (1988) to pass versions of the ordinance by voter initiative.[citation needed]

MacKinnon wrote in the Harvard Civil Rights-Civil Liberties Law Review in 1985:

And as you think about the assumption of consent that follows women into pornography, look closely some time for the skinned knees, the bruises, the welts from the whippings, the scratches, the gashes. Many of them are not simulated. One relatively soft core pornography model said, "I knew the pose was right when it hurt." It certainly seems important to the audiences that the events in the pornography be real. For this reason, pornography becomes a motive for murder, as in "snuff" films in which someone is tortured to death to make a sex film. They exist."[17]

MacKinnon represented Boreman from 1980 until Boreman's death in 2002. Civil libertarians frequently find MacKinnon's theories objectionable (see "Criticisms" section), arguing there is no evidence that sexually explicit media encourages or promotes violence against, or other measurable harm of women.[18] One laboratory study found that possible temporary effects of pornography may dissipate over time.[19]

In February 1992, the Supreme Court of Canada largely accepted MacKinnon's theories of equality, hate propaganda, and pornography, citing extensively from a brief she co-authored in a ruling againstManitoba pornography distributor Donald Butler. The Butler decision was controversial; it is sometimes implied that shipments of Dworkin's book Pornography were seized by Canadian customs agents under this ruling, as well as books by Marguerite Duras and David Leavitt;[20] the books were indeed seized by customs, but not as a consequence of Butler.[21] Successful Butler prosecutions have been undertaken against the lesbiansadomasochistic magazine Bad Attitude, as well as the owners of a gay and lesbian bookstore for selling it. Canadian authorities raided an art gallery and confiscated controversial paintings depicting child abuse. Many free speech and gay rights activists have alleged that the law is selectively enforced, targeting the LGBT community. MacKinnon represented Bosnian and Croatian women against Serbs accused of genocide since 1992. She was co-counsel, representing named plaintiff S. Kadic, in Kadic v. Karadzic and won a jury verdict of $745 million in New York City on August 10, 2000. The lawsuit (under the United States' Alien Tort Statute) established forced prostitution and forced impregnation as legally actionable acts of genocide. In MacKinnon's view, traditional approaches to human rights gloss over abuses specific to women (e.g., sexual violence), both in wartime and peacetime. MacKinnon has worked to change laws, or their interpretation and application in Mexico, Japan, Israel, and India. In 2001, MacKinnon was named co-director of the Lawyers Alliance for Women (LAW) Project, an initiative of Equality Now, an international non-governmental organization.[citation needed]

MacKinnon's work largely focuses on the difference between quality of social and economic conditions for women in both the private and public spheres of life. MacKinnon believes that society fails to recognize the existing hierarchies present within it that have subordinated women in particular for such a long time that they have been perceived as natural. “Men's forms of dominance over women have been accomplished socially as well as economically, prior to the operation of law, without express state acts, often in intimate contexts, as everyday life” (Mackinnon, 161).[22] The law often has a difficult time judging women’s inequalities, or simply is powerless to do so because of this distinction between private and public life. Much of the injustice that women experience occurs in intimate private settings as Mackinnon states above; legally, this puts them in a very vulnerable position. In MacKinnon's theories, the opposite of equality is not difference but hierarchy as social constructs. "Equality thus requires promoting equality of status for historically subordinated groups, dismantling group hierarchy." In MacKinnon's view, this requires a substantive approach to equality jurisprudence in its examination of hierarchy, whereas before, abstract notions of equality sufficed.[citation needed]

MacKinnon writes about the interrelations between theory and practice, recognizing that women's experiences have, for the most part, been ignored in both arenas. Furthermore, she uses Marxism to critique certain points in feminist theory and uses feminism to criticize Marxist theory.[23] Mackinnon saw hypocrisy in much of Marx's theory due to his failure to mention women's oppression in relation to class oppression. MacKinnon notes Marx's criticism of theory that treated class division as a spontaneous event that occurred naturally. Marx saw class as an unnatural status quo resulting from the ownership of the means of production while at the same time thinking of women's responsibility for child-rearing as a "natural" sex role. She understands epistemology as theories of knowing and politics as theories of power. She explains, "Having power means, among other things, that when someone says, 'this is how it is', it is taken as being that way. . . . Powerlessness means that when you say 'this is how it is,' it is not taken as being that way. This makes articulating silence, perceiving the presence of absence, believing those who have been socially stripped of credibility, critically contextualizing what passes for simple fact, necessary to the epistemology of a politics of the powerless."[24]

In 1996, Fred Shapiro[who?] calculated that "Feminism, Marxism, Method, and the State: Toward Feminist Jurisprudence", 8 Signs 635 (1983), was the 96th most cited article in law reviews even though it was published in a non-legal journal.[25]

During the "Feminist Sex Wars" in the 1980s, feminists opposing anti-pornography stances, such as Ellen Willis and Carole Vance, began referring to themselves as "pro-sex" or "sex-positive feminists". Sex positive feminists and anti-pornography feminists have debated over the implicit and explicit meanings of these labels. Sex-positive feminists claimed that anti-pornography ordinances contrived by MacKinnon and Dworkin called for the removal, censorship, or control over sexually explicit material.[26]

MacKinnon was engaged to Jeffrey Moussaieff Masson for several years during the early 1990s, though the relationship subsequently ended. She has refused to discuss the relationship in later interviews.[27][28]

^Dworkin, Ronald. "Women and Pornography", New York Review of Books 40, no. 17 (21 October 1993): 299. "no reputable study has concluded that pornography is a significant cause of sexual crime: many of them conclude, on the contrary, that the causes of violent personality lie mainly in childhood"